Nasal Cavity and Paranasal Sinus Cancer: Stages and Grades

Approved by the Cancer.Net Editorial Board, 05/2017

ON THIS PAGE: You will learn about how doctors describe a cancer’s growth or spread, as well as what the cancer cells look like under a microscope. This is called the stage and grade. Use the menu to see other pages.

Staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of the body.

Doctors use diagnostic tests to find out the cancer’s stage, so staging may not be complete until all of the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient’s prognosis, which is the chance of recovery. There are different stage descriptions for different types of cancer.

TNM staging system

One tool that doctors use to describe the stage is the TNM system. Doctors use the results from diagnostic tests and scans to answer these questions:

  • Tumor (T): How large is the primary tumor? Where is it located?

  • Node (N): Has the tumor spread to the lymph nodes? If so, where and how many? 

  • Metastasis (M): Has the cancer metastasized to other parts of the body? If so, where and how much?

The results are combined to determine the stage of cancer for each person.

There are 5 stages for nasal cavity and paranasal sinus cancer: stage 0 (zero) and stages I through IV (1 through 4). The stage provides a common way of describing the cancer, so doctors can work together to plan the best treatments.

Here are more details on each part of the TNM system for nasal cavity and paranasal sinus cancer.

Tumor (T)

Using the TNM system, the "T" plus a letter or number (0 to 4) is used to describe the size and location of the tumor. Some stages are also divided into smaller groups that help describe the tumor in even more detail. Specific tumor stage information is listed below.

Tumors of the paranasal sinuses are evaluated by their exact location. See the Introduction for descriptions.

Primary tumor (T) in the maxillary sinus

TX: The primary tumor cannot be evaluated.

Tis: This is a very-early-stage cancer in which cancer cells are found only in 1 layer of tissue. It is also called carcinoma (cancer) in situ.

T1: The tumor is limited to the inside of the sinus and does not erode or invade bone.

T2: The tumor erodes or invades the bone surrounding the sinuses.

T3: The tumor invades the surrounding bone, the skin of the cheek, or the other sinuses.

T4a: The tumor invades the bone surrounding the eye, the skin of the cheek, or the bones in the back of the throat.

T4b: The tumor invades any of the following: the back of the eye, the brain area, or the bones of the skull, other than those behind the nose and the back of the head.

Primary tumor (T) in the nasal cavity and ethmoid sinus

TX: The primary tumor cannot be evaluated.

Tis: This is a very-early-stage cancer in which cancer cells are found only in 1 layer of tissue. It is also called carcinoma (cancer) in situ.

T1: The tumor is limited to the inside of the sinus.

T2: The tumor extends into the nasal cavity.

T3: The tumor extends into the maxillary sinus or to the bone surrounding the eye.

T4a: The tumor has spread throughout the facial bones or into the base of the skull.

T4b: The tumor invades any of the following: the back of the eye, the brain area, or the back of the head.

Node (N)

The “N” in the TNM staging system stands for lymph nodes. These tiny, bean-shaped organs help fight infection. Lymph nodes near the head and neck are called regional lymph nodes. Lymph nodes in other parts of the body are called distant lymph nodes. Since there are many nodes in the head and neck area, the doctor’s careful evaluation of lymph nodes is an important part of staging.

Evaluation of the lymph nodes is done by the oncologist in the clinic and by a pathologist in a lab.

Clinical definition

NX: The regional lymph nodes cannot be evaluated.

N0 (N plus zero): There is no evidence of cancer in the regional lymph nodes.

N1: The cancer has spread to 1 lymph node on the same side as the primary tumor. The cancer found is 3 centimeters (cm) or smaller. It does not extend into the tissue beyond the involved lymph node, called extranodal extension (ENE).

N2a: The cancer has spread to 1 lymph node on the same side as the primary tumor. It is between 3 cm and 6 cm in size. There is no ENE.

N2b: The cancer has spread to more than 1 lymph node on the same side as the primary tumor, and all are smaller than 6 cm. There is no ENE.

N2c: The cancer has spread to more than 1 lymph node on either side of the body, and all are smaller than 6 cm. There is no ENE.

N3a: The cancer is found in at least 1 nearby lymph node and is larger than 6 cm. There is no ENE.

N3b: The cancer has spread to any node, and it has spread to the tissue surrounding the lymph node (ENE).

Pathological definition

NX: The regional lymph nodes cannot be evaluated.

N0 (N plus zero): There is no evidence of cancer in the regional lymph nodes.

N1: The cancer has spread to 1 lymph node on the same side as the primary tumor. The cancer found is 3 centimeters (cm) or smaller. It does not extend into the tissue beyond the involved lymph node, called extranodal extension (ENE).

N2a: The cancer has spread to 1 lymph node on either side of the primary tumor. It is smaller than 3 cm, and ENE is present. Or, it has spread to 1 lymph node on the same side of the primary tumor, it is between 3 cm and 6 cm in size, and there is no ENE.

N2b: The cancer has spread to more than 1 lymph node on the same side as the primary tumor, and all are smaller than 6 cm. There is no ENE.

N2c: The cancer has spread to more than 1 lymph node on either side of the body, and all are smaller than 6 cm. There is no ENE.

N3a: The cancer is found in at least 1 nearby lymph node and is larger than 6 cm. There is no ENE.

N3b: The cancer is found in 1 lymph node on the same side as the primary tumor, it is larger than 3 cm, and there is ENE. Or, the cancer has spread to many nodes on either side of the body, and there is ENE.

Metastasis (M)

The "M" in the TNM system indicates whether the cancer has spread to other parts of the body, called distant metastasis.

M0 (M plus zero): The cancer has not spread to other parts of the body.

M1: The cancer has spread to another part(s) of the body.

Grade (G)

Doctors also describe this type of cancer by its grade (G), which describes how much cancer cells look like healthy cells when viewed under a microscope.

The doctor compares the cancerous tissue with healthy tissue. Healthy tissue usually contains many different types of cells grouped together. If the cancer looks similar to healthy tissue and contains different cell groupings, it is called differentiated or a low-grade tumor. If the cancerous tissue looks very different from healthy tissue, it is called poorly differentiated or a high-grade tumor. The cancer’s grade may help the doctor predict how quickly the cancer will spread. In general, the lower the tumor’s grade, the better the prognosis.

GX: The grade cannot be evaluated.

G1: The cells look more like healthy tissue and are well differentiated.

G2: The cells are only moderately differentiated.

G3: The cells don’t resemble healthy tissue and are poorly differentiated.

Cancer stage grouping

Doctors assign the stage of the cancer by combining the T, N, and M classifications.

Stage 0: This is a very early cancer (Tis) with no spread to lymph nodes (N0) or distant metastasis (M0).

Stage I: This is a noninvasive cancer (T1) with no spread to lymph nodes (N0) and no distant metastasis (M0).

Stage II: This is an invasive cancer (T2) that has not spread to lymph nodes (N0) or to distant parts of the body (M0).

Stage III: This includes invasive cancer (T3) with no spread to regional lymph nodes (N0) and no metastasis (M0), as well as invasive cancer (T1, T2, T3) that has spread to regional lymph nodes (N1) but shows no sign of metastasis (M0).

Stage IVA: This is an invasive cancer (T4a) that either has no lymph node involvement (N0) or has spread to only 1 same-sided lymph node (N1) but with no metastasis (M0). It is also used for any cancer that is not considered very advanced (T1, T2, T3, T4a) with more significant nodal involvement (N2) but with no metastasis (M0).

Stage IVB: This is an invasive cancer (any T) that has spread lymph nodes (N3) but has no metastasis (M0). It is also used for very advanced cancer (T4b) that has not metastasized (any N, M0).

Stage IVC: This refers to any tumor (any T, any N) when there is evidence of distant spread (M1).

Recurrent: Recurrent cancer is cancer that has come back after treatment. If the cancer does return, there will be another round of tests to learn about the extent of the recurrence. These tests and scans are often similar to those done at the time of the original diagnosis.

Used with permission of the American College of Surgeons, Chicago, Illinois. The original and primary source for this information is the AJCC Cancer Staging Manual, Eighth Edition (2017) published by Springer International Publishing.

Information about the cancer’s stage and grade will help the doctor recommend a specific treatment plan. The next section in this guide is Treatment Options. You may use the menu to choose a different section to read in this guide.